The present invention relates to a pneumatic nailer wherein a plurality of paths are defined radially through the valve member and a seal between the cylinder and the valve is sucked tightly when the trigger is not squeezed.
An air valve for a conventional pneumatic nailer is shown in FIG. 1 and generally includes an end cap 11 connected to a rear end of the body 15 of the nailer and a valve member 12 is movably engaged with an annular space 111 of the end cap 11. Two seals 125, 126 are embedded to the inner and the outer periphery of the valve member 12 and are moved along the surfaces of the annular space 111. A cylinder 16 is received in the body 15 and has a flange 161 which is securely engaged with an inside of the body 15. A seal 112 is connected to the valve member 12 and contacts an end of the cylinder 16 so as to seal the conjunction portion between the cylinder 16 and the valve member 12. The end cap 11 has a tubular portion 121 which has a groove for receiving a spring 13 therein which urges the valve member 12 to let the seal 112 contact the cylinder 16. A piston 18 is movably received in the cylinder 16 and an injection rod 19 is connected to the piston 18. The piston 18 has a protrusion extending through the valve member 12 and contacting an end surface 122 on the tubular portion 121. When the user squeeze the trigger of the nailer, the valve member 12 is moved toward the tubular portion 121 and pressurized air enters the cylinder 16 to move the piston 18 to inject a nail. The seals 125, 126 will be worn out after frequent movement on the surfaces of the annular space 111. The seal 112 hits on the cylinder 16 when the pressurized air is released from release path of the nailer and the valve member 12 is pushed back by the spring 13. This could loosen the position of the seal 112. The piston 18 returns back by the air flow after the nail is injected and the protrusion hits the end surface 122 of the end cap 11. This will shank the whole assembly and leakage could happens.
In accordance with one aspect of the present invention, there is provided a air-seal structure for pneumatic nailers and the structure comprises a valve member that has a skirt portion movably engaged with an annular space of the end cap and first seals are connected to the skirt portion of the valve member. A spring is biased between the skirt portion and an inside of the annular space. A plurality of paths are defined radially through the valve member and communicate with air release passage defined in the end cap. A second seal is connected to the valve member and closes the paths. The second seal removably contacts an rear end of a cylinder in the mailer body. A cushion member is engaged with a disk member connected to an inside of the end cap and has an recess defined in a side thereof. A piston is movably received in the cylinder and an injection rod is connected to the piston. The piston has a protrusion which is disengagably engaged with the recess.
The primary object of the present invention is to provide an air-seal structure for pneumatic nailers and the structure occupies less space and effectively enhances the air-seal feature of the nailer.